Reliable assessment of liver function using LiMAx Maximilian Jara, MD, a Jan Bednarsch, a Erika Valle, a Johan Friso Lock, MD, PhD, a Maciej Malinowski, MD, PhD, a Antje Schulz, MD, PhD, a Daniel Seehofer, MD, PhD, a Tobias Jung, MD, b and Martin Stockmann, MD, PhD a, * a Department of General, Visceral and Transplantation Surgery, Charite ´ - Universita ¨tsmedizin Berlin eCampus Virchow-Klinikum, Berlin, Germany b Center for Musculoskeletal Surgery, Charite ´ - Universita ¨tsmedizin Berlin - Campus Virchow-Klinikum, Berlin, Germany article info Article history: Received 28 January 2014 Received in revised form 30 June 2014 Accepted 18 July 2014 Available online 24 July 2014 Keywords: Liver function Liver function test Intra-individual repeatability Within-subject repeatability Surgery abstract Background: 13 C-liver function breath tests can facilitate the assessment of hepatic function in-vivo and may help surgeons to identify candidates for safe liver surgery. However, their acceptance into clinical practice is dependent on evaluation of technical efficacy and repeatability. The aims of this study were to evaluate the within-subject repeatability of the LiMAx (maximum liver function capacity) test in healthy individuals and in surgical patients to determine liver function in the perioperative workup. Material and methods: The LiMAx test, which is based on intravenous injection of 13 C- methacetin at a dosage of 2 mg/kg body weight was performed in eighty-six healthy subjects to determine a reference range. Twenty-four subjects underwent repeat LiMAx testing the following day to assess within-subject repeatability. Twenty-one patients un- dergoing elective extra-abdominal surgery under general anesthesia (GA group) received pre- and post-operative examinations. Results: The normal range of LiMAx was found to be 430 Æ 86 mg/kg/h and revealed a one- sided cut-off value of 315 mg/kg/h. The intraclass correlation coefficient of the repeat LiMAx tests was 0.85 (95% confidence interval 0.69e0.93) in the control group and 0.81 (95% confidence interval 0.60e0.92) in the group of patients with GA. Conclusions: The LiMAx test shows excellent reproducibility in subjects with normal liver function. GA has no effect on test results. ª 2015 Elsevier Inc. All rights reserved. 1. Introduction Several attempts have been made to assess liver function in humans by means of dynamic functional tests. Liver function breath tests using labeled substrates (e.g., 13 C) have been shown to be safe methods to measure liver function in the clinical setting [1e3]. The perioperative assessment of liver function of patients undergoing (major) hepatic resection is crucial to identify candidates for safe liver surgery [4,5]. Methodological limitations and a perceived lack of robustness and accuracy mean that none of the approaches developed have entered routine clinical practice. Recent expert opinion has suggested further evaluation of 13 C-liver function breath tests [6,7]. 13 C-labeled methacetin, a paracetamol prodrug and sub- strate for the hepatic cytochrome P450 (CYP) 1A2 system, has * Corresponding author. Department of General, Visceral and Transplantation Surgery, Charite ´ - Universita ¨ tsmedizin Berlin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany. Tel.: þ49 30 450 55 20 01; fax: þ49 30 450 55 29 27. E-mail address: martin.stockmann@charite.de (M. Stockmann). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.JournalofSurgicalResearch.com journal of surgical research 193 (2015) 184 e189 0022-4804/$ e see front matter ª 2015 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jss.2014.07.041